The ability to crawl through long, flexible, and curved tubes has long been a challenge for engineers since numerous applications can benefit from a reliable solution. This ranges from medical applications for treatment and diagnosis to sewer pipes, gas pipes and power plants.
Current solutions often contain a payload such as a camera, that is pushed from the back by a long flexible rod or wire. This is the solution currently used in most medical applications with guide wires or catheters as used to deliver diagnosis or treatment instruments to the desired position, e.g. catheterization, colonoscopy, ureteroscopy, dilating balloon, and others.
In some type of applications it is impossible to push the active head from the back because the force required would cause buckling of the long rod or wire. One of the biggest shortcomings of current endoscopes and catheters is that they are pushed into the human body manually over a curved path, thereby causing friction, and possible injuries to the inner tissue walls of the lumen.
In search for a solution, a number of locomotion types of propulsion have been developed, which pull at the distal end of the lumen rather then pushing at the proximal end. Examples in non-medical applications include crawling vehicles and spider-like robots, such as are described in U.S. Pat. Nos. 6,824,510, and 5,090,259. In medical applications the most common solution is that of the inch worm type, that advances by means of peristaltic motion, such as is described, for instance, in U.S. Pat. Nos. 6,764,441, 4,176,662, 5,090,259, 5,662,587, 6,007,482 and 5,364,353, and in the article by P. Dario, et al., “Development and in vitro testing of a miniature robotic system for computer-assisted colonoscopy,” published in Computer Aided Surgery, Vol. 4, pp. 1-14, 1999, and in the article “A Locomotive Mechanism for a Robotic Colonoscope” by Byungkyu K, et al., published in Proceedings of the IEEE/RSJ Intl. Conference on Intelligent Robots and Systems; 2003, pp. 1373-8. Another type of medical application device is described in U.S. Pat. No. 6,702,735.
Another solution is one which imitates the locomotion of the earth-worm (Annelida), that generates waves of contraction and relaxation of alternate muscle groups (longitudinal and circular muscles), causing the worm to move forward, such as is described in the article by J. Dietrich et al., entitled “Development of a peristaltically actuated device for the minimal invasive surgery with a haptic sensor array” published in Micro- and Nanostructures of Biological Systems, Halle, Shaker-Verlag, 69-88. ISBN 3-8322-2655-9. Another solution suggested uses motion hydraulically generated close to the tip, such as is described in U.S. Patent Application 2005/0033343, for “Catheter Drive” to I. Chermoni.
Most of the above described devices have the disadvantage that a number of control lines or pneumatic tubes are required to operate the device, which complicates both the control system and the physical deployment of the device within the passageway. The device described in the above-mentioned U.S. Pat. No. 5,364,353 for “Apparatus for advancing an object through a body passage” to M. T. Corfitsen et al., and that in co-pending PCT Application No. PCT/IL2006/000925 for “Tip propelled device for motion through a passage” to the authors of the present application, on the other hand, require only one inflation tube. In U.S. Pat. No. 5,364,353, there is described a device using a single bladder and an axially expandable bellows with a throttle valve between them. A tube is provided with a lumen for the supply and removal of inflation medium to the bladder and bellows. The throttling valve ensures that the inflation of the bladder is delayed relative to the axial expansion of the bellows as pressure is applied to the inflation tube, and that the deflation of the bladder is delayed relative to an axial contraction of the bellows as pressure is released from the inflation tube, such that the device can be advanced stepwise through, for instance, a gastrointestinal canal.
In co-pending PCT Application No. PCT/IL2006/000925, there is described a device having a plurality of inflatable chambers arranged serially, and serially interconnected by means of small orifices, openings or tubes between adjacent chambers, in which at least the first and last chambers are expandable at least radially, and also optionally axially, and other intermediate chambers, if present, are expandable at least axially and also optionally radially. A tube is provided with a lumen for the supply and removal of inflation medium to the chambers. The small orifices, openings or tubes ensure that the inflation of one chamber relative to that preceding it is delayed, such that the chambers inflate sequentially as fluid is pumped into an inflation tube. Likewise, the deflation of a chamber is delayed relative to that in front of it as pressure is released from the inflation tube, such that the device can be advanced stepwise through, for instance, a gastrointestinal canal.
Many of the above described devices may have various disadvantages which limit their usefulness in one aspect or another, such that there is need for a new, distally propelled catheter head which can operate simply, over long tracts of internal passages, and without causing undue damage to the inner walls of the passages.
It is to be understood that the terms chamber, balloon, bladder and similar expressions used to describe the inflatable components of the various devices of the present application, may have been used interchangeably and even claimed thuswise, and it is to be understood that no difference is intended to be conveyed by use of one term or the other.
The disclosures of each of the publications mentioned in this section and in other sections of this application, are hereby incorporated by reference, each in its entirety.